In order to secure a workpiece to a support so as to be able to work on the workpiece or handle it more easily, a device is known which fits through two similarly dimensioned holes in the two objects, the workpiece and the support, to clamp them solidly together in a position with one face of one of the objects bearing solidly against one face of the other object and the other faces of the objects turned outwardly away from each other. This device, called a ball lock pin and sold, for example, by Carr Lane Manufacturing Co. typically comprises a tube engaged along an axis through both the aligned holes and formed with at least one radially throughgoing aperture opening outwardly of one of the outer faces and with a screwthread outward of the other outer face. A retaining element typically formed as a ball is radially displaceable in the aperture between an extended position projecting radially from the tube and engageable axially with the one outer face and a retracted position generally wholly recessed in the tube. An actuating pin axially displaceable in the tube can engage with the element to radially displace same into its extended position.
In order to insure good axially directed clamping, a nut threaded on the screwthread of the tube has a face bearing axially inward on the other outer face. Thus the tube is pushed through the aligned holes in the workpiece and support (which can be another workpiece) and the pin is actuated to extend the element. Then the nut is screwed down to secure the two objects between the element and the nut face.
The last-stage clamping is fairly difficult in that the user must normally exert considerable traction on the tube to engage the element forcibly against the outer face of the opposite side so that when the nut is turned the entire device does not rotate. When the element is a ball this rotation is a particular problem that makes it fairly difficult to get the clamp tight.